Delayed pneumatic actuator



March 6, 1962 H. D. sAMuEL, JR., ETAL 3023740 DELAYED PNEUMATIC ACTUATOR Filed May 25, 1960 .Julii- United States Patent Or 3,023,740 DELAYED PNEUMATIC ACTUATOR Hubert D. Samuel, Jr., Los Angeles, and Matthew N. Miller, Topanga, Calif., assignors to Fairchild Stratos Corporation, a corporation of Maryland Filed May 25, 1960, Ser. No. 31,587 2 Claims. (Cl. 121-38) This invention relates to a pneumatic spring type actuator and more particularly relates to a self-contained delay type actuator which may be energized subsequent to its being charged with driving fiuid.

Pneumatic actuators are well known and have been used for a wide variety of purposes, such as opening and closing valves, as catapult devices, and for use in all types of ejecting functions.

In most instances the actuator is energized at the time it is connected or otherwise coupled to the source of energizing fiuid, such as a high pressure gas.

The present invention provides a novel actuator which is self-contained in that it provides its own storage volume for the high pressure gas such as compressed air. Hence, the device may be charged and disconnected from the high pressure gas source and left to be actuated by an energizing signal at some later time. By means of a novel combination of a piston type actuator mechanism, a storage volume and a transfer valve, rapid delayed type actuation as well as reciprocation is possible with the use of only a minimum of stored gas. The device is small, of relatively simple inexpensive construction, and completely reliable in operation.

It is therefore a primary object of the present invention to provide an improved pneumatic actuator.

Another object of the present invention is to provide a delayed type pneumatic actuator or pneumatic spring.

Another object of the present invention is to provide a completely self-contained pneumatic actuator.

Still another object of the present invention is to provide a pneumatic actuator which consumes a minimum of air.

These and other objects and advantages of the invention will be more apparent upon reference to the following specification, claims, and appended drawings, wherein:

FIGURE 1 is a cross section through the novel actuator of the present invention;

FIGURE 2 is a cross section taken along line 2-2 of FIGURE 1;

FIGURE 3 is an enlarged view of the transfer valve shown in FIGURE 1;

FIGURE 4 is a cross section through the transfer valve taken along line 4-4 of FIGURE 3;

FIGURE 5 is an enlarged view of the transfer valve in the open position at the opposite end of the cylinder; and

FIGURE 6 is a fragmentary showing of a modified embodiment of the actuator of the present invention.

Referring to the drawings, FIGURES 1 and 2 show the actuator of the present invention generally indicated at 10 comprising a cylinder housing 12 defining an annular storage chamber 14 surrounding a piston chamber 16. Slidably received within chamber 16 is a reciprocating piston 18 having a piston head 20 and a piston rod 22 for connection to a valve, catapult mechanism, or other device to be actuated. High pressure gas, such as compressed air gains access to the actuator through an inlet port 24 by way of valve 26. Gas exhaust from piston chamber 16 is through outlet port 28 and through outlet valve 30. Annular storage chamber 14 communicates with piston chamber 16 by means of a plurality of annularly spaced passageways, two of which are indicated at 32 and 34 in FIGURE l.

Head 20 of piston 18 carries a transfer valve 36 which 3,023,740 Patented Mar. 6, 1962 "ice when open, provides a passage for the gas completely through the piston head from rear surface 38 to front surface 40. The body portion of the piston is provided with an annular groove 42 which receives a sear pin 44. The sear pin 44 is sldable through housing 12 and engages in the slot 42 to restrain the piston against movement and retain it in the cocked position. The pin 44 may be reciprocated away from the slot 42 as indicated by the arrows in FIGURE 1 to release the piston for movement along chamber 16.

FIGURE 3 is an enlarged fragmentary view showing a portion of the actuator of FIGURE 1 illustrating the details of the transfer valve 36. FIGURE 4 is a cross section taken along line 4-4 of FIGURE 3 drawn to an even further enlarged scale, so that the details of the transfer valve may be readily apparent. The transfer valve 36 comprises a valve pin 46 having a valve head 48 at one end resting in a valve seat 50 formed on the back surface 38 of the piston head 20. At the opposite end of pin 46 is an enlarged stop 52 for preventing movement of the pin completely through the piston head.

Transfer valve pin 46 is slidably received in a circular channel 54 passing completely through the valve head. Extending upwardly from channel 54 is a substantially rectangnlar slot 56 and downwardly from channel 54 a similar slot 58. Approximately midway of its ends pin 45 is provided with a projection or tab 60 sldable in lower slot 58. Tab 60 is adapted to engage ball 62 secured to one end of a helical compression spring 64 received in a well 66 communicating with the lower slot 58. The opposite ends of spring 64 is secured to the bottom of well 66 as indicated at 68 in FIGURE 4. Ball 66 and spring 64 bearing against tab 60 act to detent the transfer valve in both the open and closed positions.

While FIGURE 3 shows the transfer valve in the closed position with head 48 resting on seat 50, FIGURE 5 shows the transfer valve in the open position with piston head 20 at the opposite end of piston chamber 16. ln the open position, air or other gas passes beneath the head 48 and through the slots 56 and 58 to the opposite side of the piston head as indicated by the arrows in FIGURE 5. Stop 52 on the end of the transfer pin is large enough to keep the pin from falling out of the channel 54, but not so large as to prevent the air from passing outwardly between the stop and the front face 40 of the piston head.

In operation, valve 26 is opened and the storage volume 14 is charged with high pressure gas through inlet port 24. This gas may be compressed air or any other suitable compressible fluid. Valve 26 is then closed and the charge of compressed gas stored for any desired length of time in the annular chamber 14. During this storage time, piston 18 is restrained against movement by the sear pin 44 received in annular slot 42.

When the firing pin or sear pin 44 is withdrawn, that is, moved downwardly as indicated in FIGURE l, the piston 18 is free to move under the influeuce of the compressed gas passing radially inwardly from annular chamber 14 through passageways such as 32 and 34 as shown in FIGURE 1. This compressed gas acts on the back face 38 of the piston so as to drive it to the left along cylinder 16 as shown in the drawing. At this time transfer valve 36 is in the closed position as shown in FIGURE 3. When the piston is at rest and retained by sear pin 44 head 48 of the transfer valve spaces the back surface 38 of the piston from the cylinder wall so that the gas passing through passageways 32 and 34 at all times has free access to the back surface of the piston. Throughout the entire charging and actuation, valve 30 is closed.

At the end of the piston stroke, stop 52 of the transfer valve pin engages the end wall 68 of the piston chamber 3 so that the transfer valve is moved to the open position indicated in FIGURE 5. The valve, as described above, is detented by means of ball 62 and spring 66 acting against tab 60 so that the transfer valve is positively retained in. both the`open and closed positions.V The highV pressure gas in back of piston head 20 holds the piston momentarily against wall 68 and retains theV transfer valve open until some of the gas passes through Channels 56,and 58 to the, front surface 40 of the piston head.

By means of gas transfer through the transfer valve, pressure on opposite sides of the piston head is equalized and since the surface area of front face 40 is greater thantthe surface area of rear face 38 exposed to the pressure gas, the piston is moved to its original position indicated in FIGURES 1 and 3. As the head 48 of the transfervalve comes in engagement with the end wall 70 of the piston cylinder, the transfer pin is driven to the closed Vposition of FIGURE 3, and is relatched in this position by the sear pin 44. i w

After the piston has returned to its original position, and is relatched, valve 30 is opened and the gas bled off to atmosphere or vented, to other apparatus as desired through outlet port 28. Valve 30 is then closed and the actuator is ready for an additional cycle of operation.

FIGURE 6 shows a modified embodiment of the novel actuator of the present invention wherein the sear pin and annular retaining groove or slot 42 is eliminated and its function replaced by valve 72 in the single passageway 74 joining annular storage chamber 14 with the piston cylinder chamber 16. Valve 72 may take any of a wide variety of conventional forms and by way of example only, may be electrically actuated by means of suitable sealed leads passing through the walls of housing 12. Opening of valve 72 connects storage chamber 14 with the rear surface of the piston so that the compressed gas stored in chamber 14 drives the pistonl in the same manner as the embodiment shown in FIGURE 1. It is believed that the remaining portions of the cycle are apparent from the description of the embodiment of FIGURE 1, and further discussion is deemed unwarranted. v

An important gas conserving feature of the present invention is that the only air or other gas dumped overboard is the air in chamber 16 after the piston is returned to its initial position. The remaining air in chamber 14 constitutes an inital charge which reduces the quantity of air required to recharge chamber 14 to the desired pressure.

i volume or the utilization of a higher pressure than is necessary with the, present device.

The invention may be embodiedV in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore` to be considered in all respercts as illustrative It is apparent from the above that the present invention provides a novel actuator which is completely selfcontained and which may' provide any desired delay between the pneumatic charging of the actuator and the time it is actually fired or tripped. The cylindrical storage chamber stores sufficient gas for a complete cycle withv charging being accomplished between cycles. Although the device may be used for rapid actuation, it has the advantage that no large valves are required. The air or other high pressure gas used for the firing stroke is not immediately dumped Voverboard after firing, but is and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.V

What is clairned and desired' to be secured by United States Letters Patent is: 1. A fluid actuator comprising a housing having a piston chamber, a piston slidably received for reciprocation within said chamber, said piston having a start of stroke position near'one end ofsaid chamber, said housJ ing including an annular storage chamber surrounding said piston chamber, valve means for connecting said storage chamber to a source of pressurized compressible fluid, means for establishing fluid communication between said storage chamber and said one end of said piston chamber, said piston including an annular groove, a movable firing pin received in said groove to restrain said piston from movement along said piston chamber, release of said firing pin permitting compressed fluid in said storage chamber to drive said piston to the other end of said piston chamber, a normally closed transfer valve connecting the opposite sides of said piston, means for opening said-transfer valve when said piston reaches said other end of said piston chamber to equalize the pressure on opposite sides of said piston, said piston having a greater area on the side facing said other end of said piston chamber whereby pressure equalization causes said piston to be returned by said fluid tosaid start of stroke position and means for reclosing said transfer valve when said piston reaches the first end of said piston chamber, saidtransfer valve being actuated into the open and closed positions by engagement with the opposite ends of said piston chamber and being positively detented into bothl the open and closed positions. i 2. A'fiuid actuator according to claim 1 including valve means for discharging fluid from said piston chamber aftertsaid piston has returned to its start' of stroke position. i

ReferencesCited in the filerof this patent UNITED sTATEs PATENTS 513,601 Teal Jan. 30, 1894 1,00l,340 p Blauvelt Aug. 22, 1911 2,790,424 i Giladtt sApr. 30, 1957 

